Related
As I understand :host-context is used to apply styles based on selector of parent.
Lets consider a rule as follows:
:host-context(.red-theme) { background-color: red; }
same can be written using :host selector as folows:
.red-theme :host { background-color: red; }
Then whh is host-context explicitly required?
Use :host if you want to style the component custom HTML element itself.
Where as :host-context is used when you also want to have a component apply a style taking into account context in which component is rendered.
So for example, you could do: (with host-context)
<div class="red-theme">
<app-component></app-component>
</div>
where app-component
<button class="btn btn-theme">Button</button>
and the component style is defined:
:host-context(.red-theme) .btn-theme {
background: red;
}
Useful if you want to have multiple alternative themes on your web application.
:host and :host-context are not Angular features, but CSS features.
Within the demo provided at stackblitz.com/edit/angular-z3xxtu, the Angular components are merged into the DOM and allow plain old CSS selector structure like .parent :host .child { color: red; }.
This changes when using Webcomponents and ShadowDOM.
The ShadowDOM acts as a barrier and encapsulates the contained markup and style, so the .parent cannot style the things on the :host and vice versa. Note cannot is not totally true, see ::part and CSS Custom Properties.
With a structure like <parent> <my-component> ShadowDOM <child> the above CSS rule no longer works and :host-context(.parent) (which could be read as .parent :host) is needed. Sadly as of 2023-01-10 this doesn't work in Firefox and Safari.
In the above demo, :host-context(.red) { color: red; } and .red :host { color: red; } produce the same output because there's no ShadowDOM involved. On top of that, Angular transforms the invalid .test :host in the CSS to .test [_nghost-some-id] which is a valid CSS selector.
Is there a way to have a class or any selector with specific styles, and then share, import or assign those styles to a another selector. This is to avid creating multiple classes and not having to go back to the HTML code all the time to assign such classes.
For example:
.orangeText{
color:orange
}
.strongtext{
font-weight:900
}
a regular scenario would use those clases like this:
<div class="orangeText strongtext">My orange Strong Text</div>
I am looking for something like this:
.orangeText{
color:orange
}
.strongtext{
font-weight:900
}
.orangeStrongTitle{
#.orangeText; /* Import styles from .orangeText*/
#.strongtext; /* Import styles from .strongtext*/
text-decoration:underline;
}
ON HTML:
<div class="orangeStrongTitle">My orange Strong Text</div>
PLEASE NOTE THAT #.orangeText IS MY INVENTION TO GIVE AN EXAMPLE OF WHAT I WANT, I DON'T KNOW IF SUCH THING EXISTS, I WAS INSPIRED ON #import
Is this possible?
With traditional CSS it seem's that you can't.
See this topic : Is it possible to combine classes in CSS?
Unless you use LESS or SASS's 'mixin' features, there's no real way in
plain CSS to "inherit" other classes. The best you can do is apply
all three classes to your DOM element. If your problem is that you
have a ton of those classes already on a page and you want to add
properties to all of them, you can do:
.foo, .bar, .foobar {
color: red;
}
and that will apply color: red to any element that has .foo or .bar or
.foobar.
EDIT
Since you're asking for an exemple, here is how the mixin feature of SASS works :
#mixin mixin-name {
margin: 0;
padding: 0;
}
ul {
#include mixin-name;
}
Having this will compile into this :
ul {
margin: 0;
padding: 0;
}
Is it possible to make a CSS class that "inherits" from another CSS class (or more than one).
For example, say we had:
.something { display:inline }
.else { background:red }
What I'd like to do is something like this:
.composite
{
.something;
.else
}
where the ".composite" class would both display inline and have a red background
There are tools like LESS, which allow you to compose CSS at a higher level of abstraction similar to what you describe.
Less calls these "Mixins"
Instead of
/* CSS */
#header {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#footer {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
You could say
/* LESS */
.rounded_corners {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#header {
.rounded_corners;
}
#footer {
.rounded_corners;
}
You can add multiple classes to a single DOM element, e.g.
<div class="firstClass secondClass thirdclass fourthclass"></div>
Rules given in later classes (or which are more specific) override. So the fourthclass in that example kind of prevails.
Inheritance is not part of the CSS standard.
Yes, but not exactly with that syntax.
.composite,
.something { display:inline }
.composite,
.else { background:red }
Keep your common attributes together and assign specific (or override) attributes again.
/* ------------------------------------------------------------------------------ */
/* Headings */
/* ------------------------------------------------------------------------------ */
h1, h2, h3, h4
{
font-family : myfind-bold;
color : #4C4C4C;
display:inline-block;
width:900px;
text-align:left;
background-image: linear-gradient(0, #F4F4F4, #FEFEFE);/* IE6 & IE7 */
}
h1
{
font-size : 300%;
padding : 45px 40px 45px 0px;
}
h2
{
font-size : 200%;
padding : 30px 25px 30px 0px;
}
The SCSS way for the given example, would be something like:
.something {
display: inline
}
.else {
background: red
}
.composite {
#extend .something;
#extend .else;
}
More info, check the sass basics
An element can take multiple classes:
.classOne { font-weight: bold; }
.classTwo { font-famiy: verdana; }
<div class="classOne classTwo">
<p>I'm bold and verdana.</p>
</div>
And that's about as close as you're going to get unfortunately. I'd love to see this feature, along with class-aliases someday.
No you can't do something like
.composite
{
.something;
.else
}
This are no "class" names in the OO sense. .something and .else are just selectors nothing more.
But you can either specify two classes on an element
<div class="something else">...</div>
or you might look into another form of inheritance
.foo {
background-color: white;
color: black;
}
.bar {
background-color: inherit;
color: inherit;
font-weight: normal;
}
<div class="foo">
<p class="bar">Hello, world</p>
</div>
Where the paragraphs backgroundcolor and color are inherited from the settings in the enclosing div which is .foo styled. You might have to check the exact W3C specification. inherit is default for most properties anyway but not for all.
I ran into this same problem and ended up using a JQuery solution to make it seem like a class can inherit other classes.
<script>
$(function(){
$(".composite").addClass("something else");
});
</script>
This will find all elements with the class "composite" and add the classes "something" and "else" to the elements. So something like <div class="composite">...</div> will end up like so: <div class="composite something else">...</div>
You can do is this
CSS
.car {
font-weight: bold;
}
.benz {
background-color: blue;
}
.toyota {
background-color: white;
}
HTML
<div class="car benz">
<p>I'm bold and blue.</p>
</div>
<div class="car toyota">
<p>I'm bold and white.</p>
</div>
Don't forget:
div.something.else {
// will only style a div with both, not just one or the other
}
You can use the converse approach to achieve the same result - start from the composite and then remove styling using the unset keyword. For example, if you start with the following sample composition:
.composite {
color: red;
margin-left: 50px;
background-color: green
}
you can then increase selector specificity to selectively remove styles using unset:
.composite.no-color {
color: unset
}
.composite.no-margin-left {
margin-left: unset
}
.composite.no-background-color {
background-color: unset
}
Here is a JSFiddle demonstrating this approach.
One benefit of this approach is that because the specificity of the compound selectors is higher than the composite itself, you do not need all of the combinations of classes to achieve the desired results for multiple combinations:
/* Multi-unset compound selector combinations, such as the one that follows, ARE NOT NECESSARY because of the higher specificity of each individual compound selectors listed above. This keeps things simple. */
.composite.no-background-color.no-color.no-margin-left {
background-color: unset;
color: unset;
margin-left: unset
}
Furthermore, at 96% support for the unset keyword, browser coverage is excellent.
Perfect timing: I went from this question to my email, to find an article about Less, a Ruby library that among other things does this:
Since super looks just like footer, but with a different font, I'll use Less's class inclusion technique (they call it a mixin) to tell it to include these declarations too:
#super {
#footer;
font-family: cursive;
}
In Css file:
p.Title
{
font-family: Arial;
font-size: 16px;
}
p.SubTitle p.Title
{
font-size: 12px;
}
I realize this question is now very old but, here goes nothin!
If the intent is to add a single class that implies the properties of multiple classes, as a native solution, I would recommend using JavaScript/jQuery (jQuery is really not necessary but certainly useful)
If you have, for instance .umbrellaClass that "inherits" from .baseClass1 and .baseClass2 you could have some JavaScript that fires on ready.
$(".umbrellaClass").addClass("baseClass1");
$(".umbrellaClass").addClass("baseClass2");
Now all elements of .umbrellaClass will have all the properties of both .baseClasss. Note that, like OOP inheritance, .umbrellaClass may or may not have its own properties.
The only caveat here is to consider whether there are elements being dynamically created that won't exist when this code fires, but there are simple ways around that as well.
Sucks css doesn't have native inheritance, though.
Unfortunately, CSS does not provide 'inheritance' in the way that programming languages like C++, C# or Java do. You can't declare a CSS class an then extend it with another CSS class.
However, you can apply more than a single class to an tag in your markup ... in which case there is a sophisticated set of rules that determine which actual styles will get applied by the browser.
<span class="styleA styleB"> ... </span>
CSS will look for all the styles that can be applied based on what your markup, and combine the CSS styles from those multiple rules together.
Typically, the styles are merged, but when conflicts arise, the later declared style will generally win (unless the !important attribute is specified on one of the styles, in which case that wins). Also, styles applied directly to an HTML element take precedence over CSS class styles.
Don't think of css classes as object oriented classes, think of them as merely a tool among other selectors to specify which attribute classes an html element is styled by. Think of everything between the braces as the attribute class, and selectors on the left-hand side tell the elements they select to inherit attributes from the attribute class. Example:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
When an element is given the attribute class="foo", it is useful to think of it not as inheriting attributes from class .foo, but from attribute class A and attribute class B. I.e., the inheritance graph is one level deep, with elements deriving from attribute classes, and the selectors specifying where the edges go, and determining precedence when there are competing attributes (similar to method resolution order).
The practical implication for programming is this. Say you have the style sheet given above, and want to add a new class .baz, where it should have the same font-size as .foo. The naive solution would be this:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
.baz { font-size : 2em; /* attribute class C, hidden dependency! */}
Any time I have to type something twice I get so mad! Not only do I have to write it twice, now I have no way of programatically indicating that .foo and .baz should have the same font-size, and I've created a hidden dependency! My above paradigm would suggest that I should abstract out the font-size attribute from attribute class A:
.foo, .bar, .baz { font-size : 2em; /* attribute base class for A */}
.foo, .bar { font-weight : bold; /* attribute class A */}
.foo { color : green; /* attribute class B */}
The main complaint here is that now I have to retype every selector from attribute class A again to specify that the elements they should select should also inherit attributes from attribute base class A. Still, the alternatives are to have to remember to edit every attribute class where there are hidden dependencies each time something changes, or to use a third party tool. The first option makes god laugh, the second makes me want to kill myself.
That's not possible in CSS.
The only thing supported in CSS is being more specific than another rule:
span { display:inline }
span.myclass { background: red }
A span with class "myclass" will have both properties.
Another way is by specifying two classes:
<div class="something else">...</div>
The style of "else" will override (or add) the style of "something"
As others have said, you can add multiple classes to an element.
But that's not really the point. I get your question about inheritance. The real point is that inheritance in CSS is done not through classes, but through element hierarchies. So to model inherited traits you need to apply them to different levels of elements in the DOM.
While direct inheritance isn't possible.
It is possible to use a class (or id) for a parent tag and then use CSS combinators to alter child tag behaviour from it's heirarchy.
p.test{background-color:rgba(55,55,55,0.1);}
p.test > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
<p class="test"><span>One <span>possible <span>solution <span>is <span>using <span>multiple <span>nested <span>tags</span></span></span></span></span></span></span></span></p>
I wouldn't suggest using so many spans like the example, however it's just a proof of concept. There are still many bugs that can arise when trying to apply CSS in this manner. (For example altering text-decoration types).
I was looking for that like crazy too and I just figured it out by trying different things :P... Well you can do it like that:
composite.something, composite.else
{
blblalba
}
It suddenly worked for me :)
In specific circumstances you can do a "soft" inheritance:
.composite
{
display:inherit;
background:inherit;
}
.something { display:inline }
.else { background:red }
This only works if you are adding the .composite class to a child element. It is "soft" inheritance because any values not specified in .composite are not inherited obviously. Keep in mind it would still be less characters to simply write "inline" and "red" instead of "inherit".
Here is a list of properties and whether or not they do this automatically:
https://www.w3.org/TR/CSS21/propidx.html
Less and Sass are CSS pre-processors which extend CSS language in valuable ways. Just one of many improvements they offer is just the option you're looking for. There are some very good answers with Less and I will add Sass solution.
Sass has extend option which allows one class to be fully extended to another one. More about extend you can read in this article
I think this one is a better solution:
[class*=“button-“] {
/* base button properties */
}
.button-primary { ... }
.button-plain { ... }
Actually what you're asking for exists - however it's done as add-on modules. Check out this question on Better CSS in .NET for examples.
Check out Larsenal's answer on using LESS to get an idea of what these add-ons do.
CSS doesn't really do what you're asking. If you want to write rules with that composite idea in mind, you may want to check out compass. It's a stylesheet framework which looks similar to the already mentioned Less.
It lets you do mixins and all that good business.
For those who are not satisfied with the mentioned (excellent) posts, you can use your programming skills to make a variable (PHP or whichever) and have it store the multiple class names.
That's the best hack I could come up with.
<style>
.red { color: red; }
.bold { font-weight: bold; }
</style>
<? define('DANGERTEXT','red bold'); ?>
Then apply the global variable to the element you desire rather than the class names themselves
<span class="<?=DANGERTEXT?>"> Le Champion est Ici </span>
Have a look at CSS compose:
https://bambielli.com/til/2017-08-11-css-modules-composes/
according to them:
.serif-font {
font-family: Georgia, serif;
}
.display {
composes: serif-font;
font-size: 30px;
line-height: 35px;
}
I use it in my react project.
If you want a more powerful text preprocessor than LESS, check out PPWizard:
http://dennisbareis.com/ppwizard.htm
Warning the website is truly hideous and there's a small learning curve, but it's perfect for building both CSS and HTML code via macros. I've never understood why more web coders don't use it.
You can achieve what you want if you preprocess your .css files through php.
...
$something='color:red;'
$else='display:inline;';
echo '.something {'. $something .'}';
echo '.else {'. $something .'}';
echo '.somethingelse {'. $something .$else '}';
...
Is there a way to import the styling of a single CSS selector into another CSS selector and add to it or rewrite properties from it.
Let's say:
.original_class{
background:black;
color:white;
}
.overwrite{
#import(.original_class); /* I know this doesn't work */
color:blue;
border:1px solid green;
}
I can accomplish this by just redeclaring the .original_class and assigning new values (since CSS styles are rewritten from top to bottom), but this will replace the attributes of the original CSS class. What I want is to inherit its properties into another class without having to write them again (duplicate).
Not directly, no.
You could do something like this in your HTML:
<div class="original_class overwrite">...</div>
This will have the same effect, but you will have to do this for every element you want styled that way.
There is also the option of using a CSS pre-processor, like SASS, which supports inheritance/mixins.
You can add the .overwrite selector to the first rule by separating it from the existing selector with a comma (grouping selectors), so the selector rule becomes .original_class, .overwrite:
.original_class,
.overwrite {
background: black;
color: white;
}
.overwrite {
color: blue;
border: 1px solid green;
}
Also, when you write:
this will replace the attributes of the original CSS class
there is no such thing as attributes and class in CSS, not with the intended meaning of OOP I guess. There are rules, selector rules (to select HTML id, classes, elements, attributes and other pseudos), declarations, properties and values.
Unfortunately not. At least not without one of those fancy CSS plugin thingies that I wouldn't touch with a mile-long pole...
Of course, there's nothing stopping you having multiple classes on a single element.
Is it possible to make a CSS class that "inherits" from another CSS class (or more than one).
For example, say we had:
.something { display:inline }
.else { background:red }
What I'd like to do is something like this:
.composite
{
.something;
.else
}
where the ".composite" class would both display inline and have a red background
There are tools like LESS, which allow you to compose CSS at a higher level of abstraction similar to what you describe.
Less calls these "Mixins"
Instead of
/* CSS */
#header {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#footer {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
You could say
/* LESS */
.rounded_corners {
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
}
#header {
.rounded_corners;
}
#footer {
.rounded_corners;
}
You can add multiple classes to a single DOM element, e.g.
<div class="firstClass secondClass thirdclass fourthclass"></div>
Rules given in later classes (or which are more specific) override. So the fourthclass in that example kind of prevails.
Inheritance is not part of the CSS standard.
Yes, but not exactly with that syntax.
.composite,
.something { display:inline }
.composite,
.else { background:red }
Keep your common attributes together and assign specific (or override) attributes again.
/* ------------------------------------------------------------------------------ */
/* Headings */
/* ------------------------------------------------------------------------------ */
h1, h2, h3, h4
{
font-family : myfind-bold;
color : #4C4C4C;
display:inline-block;
width:900px;
text-align:left;
background-image: linear-gradient(0, #F4F4F4, #FEFEFE);/* IE6 & IE7 */
}
h1
{
font-size : 300%;
padding : 45px 40px 45px 0px;
}
h2
{
font-size : 200%;
padding : 30px 25px 30px 0px;
}
The SCSS way for the given example, would be something like:
.something {
display: inline
}
.else {
background: red
}
.composite {
#extend .something;
#extend .else;
}
More info, check the sass basics
An element can take multiple classes:
.classOne { font-weight: bold; }
.classTwo { font-famiy: verdana; }
<div class="classOne classTwo">
<p>I'm bold and verdana.</p>
</div>
And that's about as close as you're going to get unfortunately. I'd love to see this feature, along with class-aliases someday.
No you can't do something like
.composite
{
.something;
.else
}
This are no "class" names in the OO sense. .something and .else are just selectors nothing more.
But you can either specify two classes on an element
<div class="something else">...</div>
or you might look into another form of inheritance
.foo {
background-color: white;
color: black;
}
.bar {
background-color: inherit;
color: inherit;
font-weight: normal;
}
<div class="foo">
<p class="bar">Hello, world</p>
</div>
Where the paragraphs backgroundcolor and color are inherited from the settings in the enclosing div which is .foo styled. You might have to check the exact W3C specification. inherit is default for most properties anyway but not for all.
I ran into this same problem and ended up using a JQuery solution to make it seem like a class can inherit other classes.
<script>
$(function(){
$(".composite").addClass("something else");
});
</script>
This will find all elements with the class "composite" and add the classes "something" and "else" to the elements. So something like <div class="composite">...</div> will end up like so: <div class="composite something else">...</div>
You can do is this
CSS
.car {
font-weight: bold;
}
.benz {
background-color: blue;
}
.toyota {
background-color: white;
}
HTML
<div class="car benz">
<p>I'm bold and blue.</p>
</div>
<div class="car toyota">
<p>I'm bold and white.</p>
</div>
Don't forget:
div.something.else {
// will only style a div with both, not just one or the other
}
You can use the converse approach to achieve the same result - start from the composite and then remove styling using the unset keyword. For example, if you start with the following sample composition:
.composite {
color: red;
margin-left: 50px;
background-color: green
}
you can then increase selector specificity to selectively remove styles using unset:
.composite.no-color {
color: unset
}
.composite.no-margin-left {
margin-left: unset
}
.composite.no-background-color {
background-color: unset
}
Here is a JSFiddle demonstrating this approach.
One benefit of this approach is that because the specificity of the compound selectors is higher than the composite itself, you do not need all of the combinations of classes to achieve the desired results for multiple combinations:
/* Multi-unset compound selector combinations, such as the one that follows, ARE NOT NECESSARY because of the higher specificity of each individual compound selectors listed above. This keeps things simple. */
.composite.no-background-color.no-color.no-margin-left {
background-color: unset;
color: unset;
margin-left: unset
}
Furthermore, at 96% support for the unset keyword, browser coverage is excellent.
Perfect timing: I went from this question to my email, to find an article about Less, a Ruby library that among other things does this:
Since super looks just like footer, but with a different font, I'll use Less's class inclusion technique (they call it a mixin) to tell it to include these declarations too:
#super {
#footer;
font-family: cursive;
}
In Css file:
p.Title
{
font-family: Arial;
font-size: 16px;
}
p.SubTitle p.Title
{
font-size: 12px;
}
I realize this question is now very old but, here goes nothin!
If the intent is to add a single class that implies the properties of multiple classes, as a native solution, I would recommend using JavaScript/jQuery (jQuery is really not necessary but certainly useful)
If you have, for instance .umbrellaClass that "inherits" from .baseClass1 and .baseClass2 you could have some JavaScript that fires on ready.
$(".umbrellaClass").addClass("baseClass1");
$(".umbrellaClass").addClass("baseClass2");
Now all elements of .umbrellaClass will have all the properties of both .baseClasss. Note that, like OOP inheritance, .umbrellaClass may or may not have its own properties.
The only caveat here is to consider whether there are elements being dynamically created that won't exist when this code fires, but there are simple ways around that as well.
Sucks css doesn't have native inheritance, though.
Unfortunately, CSS does not provide 'inheritance' in the way that programming languages like C++, C# or Java do. You can't declare a CSS class an then extend it with another CSS class.
However, you can apply more than a single class to an tag in your markup ... in which case there is a sophisticated set of rules that determine which actual styles will get applied by the browser.
<span class="styleA styleB"> ... </span>
CSS will look for all the styles that can be applied based on what your markup, and combine the CSS styles from those multiple rules together.
Typically, the styles are merged, but when conflicts arise, the later declared style will generally win (unless the !important attribute is specified on one of the styles, in which case that wins). Also, styles applied directly to an HTML element take precedence over CSS class styles.
Don't think of css classes as object oriented classes, think of them as merely a tool among other selectors to specify which attribute classes an html element is styled by. Think of everything between the braces as the attribute class, and selectors on the left-hand side tell the elements they select to inherit attributes from the attribute class. Example:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
When an element is given the attribute class="foo", it is useful to think of it not as inheriting attributes from class .foo, but from attribute class A and attribute class B. I.e., the inheritance graph is one level deep, with elements deriving from attribute classes, and the selectors specifying where the edges go, and determining precedence when there are competing attributes (similar to method resolution order).
The practical implication for programming is this. Say you have the style sheet given above, and want to add a new class .baz, where it should have the same font-size as .foo. The naive solution would be this:
.foo, .bar { font-weight : bold; font-size : 2em; /* attribute class A */}
.foo { color : green; /* attribute class B */}
.baz { font-size : 2em; /* attribute class C, hidden dependency! */}
Any time I have to type something twice I get so mad! Not only do I have to write it twice, now I have no way of programatically indicating that .foo and .baz should have the same font-size, and I've created a hidden dependency! My above paradigm would suggest that I should abstract out the font-size attribute from attribute class A:
.foo, .bar, .baz { font-size : 2em; /* attribute base class for A */}
.foo, .bar { font-weight : bold; /* attribute class A */}
.foo { color : green; /* attribute class B */}
The main complaint here is that now I have to retype every selector from attribute class A again to specify that the elements they should select should also inherit attributes from attribute base class A. Still, the alternatives are to have to remember to edit every attribute class where there are hidden dependencies each time something changes, or to use a third party tool. The first option makes god laugh, the second makes me want to kill myself.
That's not possible in CSS.
The only thing supported in CSS is being more specific than another rule:
span { display:inline }
span.myclass { background: red }
A span with class "myclass" will have both properties.
Another way is by specifying two classes:
<div class="something else">...</div>
The style of "else" will override (or add) the style of "something"
As others have said, you can add multiple classes to an element.
But that's not really the point. I get your question about inheritance. The real point is that inheritance in CSS is done not through classes, but through element hierarchies. So to model inherited traits you need to apply them to different levels of elements in the DOM.
While direct inheritance isn't possible.
It is possible to use a class (or id) for a parent tag and then use CSS combinators to alter child tag behaviour from it's heirarchy.
p.test{background-color:rgba(55,55,55,0.1);}
p.test > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
p.test > span > span > span > span > span > span > span > span{background-color:rgba(55,55,55,0.1);}
<p class="test"><span>One <span>possible <span>solution <span>is <span>using <span>multiple <span>nested <span>tags</span></span></span></span></span></span></span></span></p>
I wouldn't suggest using so many spans like the example, however it's just a proof of concept. There are still many bugs that can arise when trying to apply CSS in this manner. (For example altering text-decoration types).
I was looking for that like crazy too and I just figured it out by trying different things :P... Well you can do it like that:
composite.something, composite.else
{
blblalba
}
It suddenly worked for me :)
In specific circumstances you can do a "soft" inheritance:
.composite
{
display:inherit;
background:inherit;
}
.something { display:inline }
.else { background:red }
This only works if you are adding the .composite class to a child element. It is "soft" inheritance because any values not specified in .composite are not inherited obviously. Keep in mind it would still be less characters to simply write "inline" and "red" instead of "inherit".
Here is a list of properties and whether or not they do this automatically:
https://www.w3.org/TR/CSS21/propidx.html
Less and Sass are CSS pre-processors which extend CSS language in valuable ways. Just one of many improvements they offer is just the option you're looking for. There are some very good answers with Less and I will add Sass solution.
Sass has extend option which allows one class to be fully extended to another one. More about extend you can read in this article
I think this one is a better solution:
[class*=“button-“] {
/* base button properties */
}
.button-primary { ... }
.button-plain { ... }
Actually what you're asking for exists - however it's done as add-on modules. Check out this question on Better CSS in .NET for examples.
Check out Larsenal's answer on using LESS to get an idea of what these add-ons do.
CSS doesn't really do what you're asking. If you want to write rules with that composite idea in mind, you may want to check out compass. It's a stylesheet framework which looks similar to the already mentioned Less.
It lets you do mixins and all that good business.
For those who are not satisfied with the mentioned (excellent) posts, you can use your programming skills to make a variable (PHP or whichever) and have it store the multiple class names.
That's the best hack I could come up with.
<style>
.red { color: red; }
.bold { font-weight: bold; }
</style>
<? define('DANGERTEXT','red bold'); ?>
Then apply the global variable to the element you desire rather than the class names themselves
<span class="<?=DANGERTEXT?>"> Le Champion est Ici </span>
Have a look at CSS compose:
https://bambielli.com/til/2017-08-11-css-modules-composes/
according to them:
.serif-font {
font-family: Georgia, serif;
}
.display {
composes: serif-font;
font-size: 30px;
line-height: 35px;
}
I use it in my react project.
If you want a more powerful text preprocessor than LESS, check out PPWizard:
http://dennisbareis.com/ppwizard.htm
Warning the website is truly hideous and there's a small learning curve, but it's perfect for building both CSS and HTML code via macros. I've never understood why more web coders don't use it.
You can achieve what you want if you preprocess your .css files through php.
...
$something='color:red;'
$else='display:inline;';
echo '.something {'. $something .'}';
echo '.else {'. $something .'}';
echo '.somethingelse {'. $something .$else '}';
...